\vspace is swallowing my column

I am using

\vspace*{1cm}

in my table.. Unfortunately, the column seems to have dissapeared at the location where I am placing my /vscpace..

See the picture

   \multirow{3}{*}{Rayleigh }  & \multicolumn{1}{c|}{$\mathop{\sigma
}\nolimits^{2} =\sqrt{\frac{1}{2n} \sum
_{i=1}^{n}\mathop{v}\nolimits_{i}^{2}  }$}
\\\vspace{0.5cm}
                           &      $\gamma $: continuous location parameter                                         \\\vspace{0.5cm}
                           & $\sigma$: is the continuous scale
                           parameter\\\hline